﻿using System;
using System.Text;
using System.Security.Cryptography;
using System.IO;

namespace ShopMall.Common
{
    /// <summary>
    /// 密钥加密
    /// </summary>
    public sealed class DesClass
    {
        /// <summary>
        /// 加密方法
        /// </summary>
        /// <param name="pToEncrypt">需要加密字符串</param>
        /// <param name="sKey">密钥</param>
        /// <returns>加密字符串</returns>
        public static string Encrypt(string pToEncrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            //把字符串放到byte数组中
            //原来使用的UTF8编码，我改成Unicode编码了，不行
            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);

            //建立加密对象的密钥和偏移量
            //使得输入密码必须输入英文文本
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);

            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                ret.AppendFormat("{0:X2}", b);
            }
            return ret.ToString();
        }

        /// <summary>
        /// 解密方法
        /// </summary>
        /// <param name="pToDecrypt">需要解密字符串</param>
        /// <param name="sKey">密钥</param>
        /// <returns>字符串</returns>
        public static string Decrypt(string pToDecrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
            for (int x = 0; x < pToDecrypt.Length / 2; x++)
            {
                int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }

            //建立加密对象的密钥和偏移量，此值重要，不能修改
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            //CreateDecrypt使用的是流对象，必须把解密后的文本变成流对象
            return System.Text.Encoding.Default.GetString(ms.ToArray());
        }

        /// <summary>
        /// 设置密钥
        /// </summary>
        /// <returns>密钥</returns>
        public static string SetKey()
        {
            string sKey = "";
            int[] tmp = new int[8] { 212, 33, 96, 164, 10, 241, 142, 199 };
            foreach (int i in tmp)
            {
                sKey += ((char)i).ToString();
            }

            return sKey;
        }
    }
}
